This application is based upon and claims the benefit of Japanese Patent Applications No. 2000-380634, filed on Dec. 14, 2000, No. 2001-195375, filed on Jun. 27, 2001, and No. 2001-333021, filed on Oct. 30, 2001, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a manufacturing method of a multilayer substrate, specifically of a multilayer substrate having electrodes formed at both sides thereof.
2. Related Art
Heretofore, a manufacturing method of a multilayer substrate, which employs a so-called double-sided substrate in which conductor patterns connected with each other by interlayer connection are formed on both sides thereof, is known as a manufacturing method of a multilayer substrate having electrodes formed on both sides thereof to achieve electrical connection.
For example, a manufacturing method of a multilayer substrate is disclosed in JP-A-2000-38464. In this document, a manufacturing method of a multilayer substrate is disclosed, in which a plurality of double-sided substrates, each of which has an interlayer connection, are produced and laminated with a film insulator to which a treatment capable of an interlayer connection is carried out interposed therebetween, so that a multilayer substrate is produced that has electrodes on both sides thereof. Moreover, a manufacturing method of a multilayer substrate is disclosed, in which a double-sided substrate having an interlayer connection is produced, and single-sided conductor patterned films to which a treatment capable of an interlayer connection is carried out are laminated on both sides of the double-sided substrate, so that so that a multilayer substrate is produced that has electrodes on both sides thereof.
However, in the above-described prior art, the double-sided substrate (double-sided conductor patterned film) and the film insulator (a film without patterned conductor) are respectively formed, and combined with each other to form the multilayer substrate having the electrodes on the both sides thereof. Alternatively, the double-sided substrate (double-sided conductor patterned film) and the single-sided conductor patterned substrate are respectively formed, and combined with each other to form the multilayer substrate having the electrodes on the both sides thereof. Consequently, there is a problem in which processing steps are complicated, and production cost becomes high.
The present invention has been made in view of the above-mentioned problem, and an object thereof is to provide a manufacturing method of multilayer substrate that can be simplified and reduced in producing cost.
To achieve the object above described, according to a first aspect of the present invention, a step for laminating single-sided conductor patterned films, each of which has a resin film and a conductor pattern formed only on a single side of the resin film for forming a laminated films, and a step for removing at least a portion of a surface resin film that covers a portion of the conductor pattern to be an electrode in a single-sided conductor patterned film, at a side of the laminated films where the resin film is disposed at a surface thereof, are comprised in a manufacturing method. In this method, electrodes are formed respectively at both principal surfaces of a multilayer substrate composed of the single-sided conductor patterned films, and the electrodes are composed of conductor patterns, respectively.
According to this method, the single-sided conductor patterned films, each of which has the resin film and the conductor pattern formed only on the single side of the resin film, are laminated to form the laminated films, at least the portion of the surface resin film is removed so as to expose the electrode, and therefore the multilayer substrate with the electrodes formed at the both principal surfaces thereof can be produced. Therefore, it is unnecessary to produce the double-sided substrate in midstream of the manufacturing process, whereby it is unnecessary to provide a double-sided substrate forming process. Thus, the manufacturing process is not complicated and can be reduced in cost.
According to a second aspect of the present invention, a step for forming a resist film on a surface of the laminated films where the conductor pattern is exposed, and a step for forming a hole in the resist film at a region corresponding to a location where the electrode is to be formed are comprised in the manufacturing method.
According to this method, the surface of the laminated single-sided conductor patterned films where the conductor pattern is exposed can be covered with the resist film. Therefore, the conductor pattern can be protected except the location where the electrode is to be formed.
According to a third aspect of the present invention, the resist film is composed of the same material as the resin film.
According to this, since the resist film is composed of the same material as the resin film, the resist film is easily attached to the resin film. Therefore, the multilayer substrate with the resist film kept certainly can be obtained.
According to a fourth aspect of the present invention, the resin film is composed of a thermoplastic resin, wherein after the laminating step at which the single-sided conductor patterned films are laminated, mutual adhesion between each of the single-sided conductor patterned films is performed by applying pressure to the both principal surfaces of the substrate while heating.
According to this method, the respective single-sided conductor patterned films can adhere with each other all at once. Therefore, the manufacturing method can be simplified so that time for manufacturing can be shortened, and therefore, the manufacturing cost can be further reduced.
According to a fifth aspect of the present invention, the resin film is composed of a thermoplastic resin, wherein after the single-sided conductor patterned films are laminated and the resist is formed, mutual adhesion between each of the single-sided conductor patterned films and between the resist film and an adjoining single-sided conductor patterned film is performed by pressing both principal surfaces of the substrate while heating.
According to this method, the respective single-sided conductor patterned films and the resist film can adhere with each other all at once. Therefore, the manufacturing method can be simplified so that time for manufacturing can be shortened, and therefore, the manufacturing cost can be further reduced.
According to a six aspect of the present invention, the substrate is heated up at a temperature where an elastic modulus of the thermoplastic resin is in a range from 1 to 1000 MPa in applying pressure and heat to the multilayer substrate.
According to this method, the resin film is heated up with pressure so as to be sufficiently lowered in elastic modulus, i.e., in such a degree from 1 to 1000 MPa, so that the single-sided conductor patterned films surely adhere with each other.
According to a seventh aspect of the present invention, except a single-sided conductor patterned film having a resin film constituting the principal surface of the multilayer substrate, each single-sided conductor patterned film has a via hole through which the conductor pattern as a bottom face is exposed and, which is filled with a conductive paste so that respective conductor patterns of adjacent single-sided conductor patterned films are electrically connected with each other.
According to this method, an interlayer electrical connection between each of the conductor patterns in the multilayer substrate can be secured by the conductive paste in the via hole.
According to a eighth aspect of the present invention, a step for laminating single-sided conductor patterned films, each of which has a resin film, a conductor pattern formed only on a single side of the resin film and a via hole that is formed at a predetermined location and filled with an interlayer connection material, wherein an exposed conductor pattern of the single-sided conductor patterned film, which is located on a first surface of a laminated single-sided conductor patterned films, is formed as a first conductive foil that covers a resin film of the single-sided conductor patterned film entirely, a step for forming a second conductive foil on a surface resin film which constitutes a second surface of the laminated single-sided conductor patterned films, so as to cover the surface resin film entirely, and a step for patterning the conductive foils disposed on both sides of the laminated single-sided conductor patterned films so as to form first and second conductor patterns, are comprised in a manufacturing method. In this method, electrodes are formed by the first and second conductor patterns on the first and second surfaces of a multilayer substrate which is formed by laminating the single-sided conductor patterned films.
According to this method, the single-sided conductor patterned films, each of which has the resin film, the conductor pattern formed only on the single side of the resin film and the via hole that is formed at the predetermined location and filled with an interlayer connection material, are laminated, and the first and second conductive foils covers the both sides disposed at an outermost of the laminated single-sided conductor patterned films, the conductive foils are patterned, whereby the multilayer substrate with the electrodes at the both sides thereof can be produced. Therefore, it is unnecessary to produce a substrate with conductor patterns on both sides thereof in midstream of a manufacturing process. Thus, the manufacturing process is not complicated and can be reduced in cost.
According to a ninth aspect of the present invention, resist films are formed on the shaped conductor patterns at the both sides of the multilayer substrate, the resist films are composed of the same material as the resin film.
According to this, since the resist films are composed of the same material as the resin film formed on the single-sided conductor patterned film, the resist films easily adhere to the resin film. Therefore, the multilayer substrate with the resist films kept certainly can be obtained.
Incidentally, as described in a tenth aspect of the present invention, the first and second conductive foils may be patterned so that only lands remain as electrodes. In this case, since wiring patterns are not formed on the both sides of the multilayer substrate, it is unnecessary to form resist films to protect and insulate the wiring patterns. Thus, the manufacturing process can be further simplified.
According to an eleventh aspect of the present invention, the resin film is composed of a thermoplastic resin, after the conductive foils are formed on the both sides of the multilayer substrate, the respective single-sided conductor patterned films adhere with each other by pressing the multilayer substrate from its both surfaces while heating.
According to this method, the respective single-sided conductor patterned films can be mutually adhered all at once. Therefore, the manufacturing method can be simplified so that time for manufacturing can be shortened, and therefore, the manufacturing cost can be further reduced.
According to a twelfth aspect of the present invention, the multilayer substrate is heated up at a temperature where an elastic modulus of the thermoplastic resin is in a range from 1 to 1000 MPa in applying pressure and heat to the multilayer substrate.
According to this method, the resin film is heated up while applying pressure so as to be sufficiently lowered in elastic modulus, i.e., in such a degree from 1 to 1000 MPa, so that the single-sided conductor patterned films are surely adhered with each other.
According to thirteenth aspect of the present invention, the interlayer connection material is a conductive paste, and said via hole has a bottom constituted by the conductor pattern, so that respective conductor patterns of adjacent single-sided conductor patterned films are electrically connected with each other through the conductive paste.
According to this method, an interlayer electrical connection between each of the conductor patterns in the multilayer substrate can be secured by the conductive paste in the via hole.
According to a fourteenth aspect of the present invention, a manufacturing method of multilayer substrate comprises laminating single-sided conductor patterned films, each of which has a resin film, a conductor pattern formed only on a single side of the resin film and a via hole which is formed at a predetermined location and filled with an interlayer connection material, and adhering the single-sided conductor patterned films to each other to form a multilayer substrate, wherein an arbitrary two of single-sided conductor patterned films are laminated so that surfaces thereof on which the conductor patterns are not formed face with each other, while remaining single-sided conductor patterned films are laminated in such a manner that a surface on which the conductor pattern is formed and a surface on which the conductor pattern is not formed face with each other, whereby electrode are formed by the conductive patterns at both sides of the multilayer substrate.
According to this method, when the single-sided conductor patterned films, each of which has a resin film, a conductor pattern formed only on a single side of the resin film and a via hole that is filled with an interlayer connection material, are laminated, only at one portion in the laminated single-sided conductor patterned films, adjoining single-sided conductor patterned films are laminated so that surfaces thereof on which the conductor patterns are not formed face with each other to thereby dispose the conductor patterns so as to face outsides, while the single-sided conductor patterned films in the remaining single-sided conductor patterned films are laminated in a same direction with respect to an adjoining single-sided conductor patterned films, i.e., are laminated so that the conductor patterns face outwardly. As a result, the multilayer substrate with electrodes formed at the both sides thereof can be produced.
Therefore, it is unnecessary to produce the double-sided substrate in midstream of the manufacturing process. Thus, the manufacturing process is not complicated and can be reduced in cost.
According to a fifteenth aspect of the present invention, resin films are formed on conductor patterns disposed on both sides of the multilayer substrate, the resist films are composed of the same material as the resin film.
According to this, since the resist films are composed of the same material as the resin film formed on the single-sided conductor patterned film, the resist films easily adhere to the resin film. Therefore, the multilayer substrate with the resist films kept certainly can be obtained.
Incidentally, as described in a sixteenth aspect of the present invention, the conductor patterns, formed on the both sides of the multilayer substrate, can be only formed by lands to be electrodes. In this case, since wiring patterns are not formed on the both sides of the multilayer substrate, it is unnecessary to form resist films to protect and insulate the wiring patterns. Thus, the manufacturing process can be further simplified.
According to a seventeenth aspect of the present invention, the resin film is composed of a thermoplastic resin, after the conductor patterns exposed at the both sides of the multilayer substrate are formed as conductive foils, respectively, which cover the resin films entirely, the respective single-sided conductor patterned films adhere with each other by pressing the multilayer substrate from its both surfaces while heating. After this, the electrodes are formed by patterning the conductive foils.
According to this method, the respective single-sided conductor patterned films can adhere with each other all at once. Moreover, this method improves mold release characteristic caused between the multilayer substrate and a press apparatus to apply the pressure.
According to eighteenth aspect of the present invention, the resin film is composed of a thermoplastic resin, after conductor patterns disposed on all of single-sided conductor patterned films are patterned into predetermined shapes, the single-sided conductor patterned films are adhered with each other by applying pressure the multilayer substrate from its both sides while heating.
According to this, the respective single-sided conductor patterned films can adhere with each other all at once. Moreover, it is unnecessary to conduct the patterning step after the attaching step. Therefore, the manufacturing method can be simplified, time for manufacturing can be shortened, and therefore, the manufacturing cost can be further reduced.
According to a nineteenth aspect of the present invention, the substrate is heated up at a temperature where an elastic modulus of the thermoplastic resin is in a range from 1 to 1000 MPa in applying pressure and heat to the multilayer substrate.
According to this method, the resin film is heated up while applying pressure so as to be sufficiently lowered in elastic modulus, i.e., in such a degree from 1 to 1000 MPa, in the pressing step, so that the single-sided conductor patterned films surely adhere with each other.
According to a twentieth aspect of the present invention, the interlayer connection material is a conductive paste, and each single-sided conductor patterned film has a via hole through which the conductor pattern as a bottom face is exposed and, which is filled with the conductive paste so that respective conductor patterns of adjacent single-sided conductor patterned films are electrically connected with each other through the conductive paste.
According to this method, an interlayer electrical connection between each of the conductor patterns in the multilayer substrate can be secured by the conductive paste in the via hole.
Incidentally, twenty-first to twenty-fourth aspects of the present invention resolve the problem described below.
Heretofore, via holes formed in general multilayer substrate approximately have a circular shape in identical diameter. When the multilayer substrate is formed by pressing a laminated resin films (isolation base material) while heating, if interlayer connection materials, which are disposed in a pair of via holes respectively formed in an adjoining two of the resin films, directly connected with each other without land portions or the like interposed therebetween, there can be a case where centers of each of the pair of via holes are displaced with each other by fluctuation in location of each of the resin films in laminating and pressing while heating.
In this case, when each of the pair of the via holes has a circular shape, there can be a case where a cross sectional area of the interlayer connection material filled in the via hole in a connecting point of the pair of via holes. In this case, such a problem occurs that resistance of interlayer connection increases.
To solve the above-mentioned problem, according to the twenty-first aspect of the present invention, via holes of the single-sided conductor patterned films that are laminated so that surfaces thereof on which the conductor patterns are not formed face with each other, are formed approximately in an elliptical shape, and said elliptical-shaped via holes are overlapped with each other so that long axes thereof are disposed in orthogonal to one another.
Moreover, according to the twenty-second aspect of the present invention, via holes of the single-sided conductor patterned films that are laminated so that surfaces thereof on which the conductor patterns are not formed face with each other, are formed in a radial shape having three or more liner portions which radially extend from a center portion, and the radial-shaped via holes are overlapped with each other.
According to these, even if centers of the via holes, disposed in the two of the single-sided conductor patterned films that are laminated so that surfaces thereof on which the conductor patterns are not formed face with each other, are slightly displaced from each other, the interlayer connection material can secure a predetermined cross sectional area thereof at the connecting point of the via holes. Therefore, the resistance of interlayer connection can be prevented from increasing.
Moreover, according to a twenty-third aspect of the present invention, the radial-shaped via holes in the twenty-second aspect may, concretely, have a crisscross pattern composed of four liner portions.
According to a twenty-fourth aspect of the present invention, via holes respectively formed in said predetermined number of single-sided conductor patterned films have an approximate circular shape. The via holes of single-sided conductor patterned films that are laminated so that surfaces thereof on which the conductor patterns are not formed face with each other, have a diameter larger than that of the via holes formed in said remaining single-sided conductor patterned films. Moreover, the via holes are overlapped with each other when the arbitrary two of the predetermined number of single-sided conductor patterned films are laminated.
Also by this method, even if centers of the via holes, disposed in the two of the single-sided conductor patterned films that are laminated so that surfaces thereof on which the conductor patterns are not formed face with each other, are slightly displaced with each other, the interlayer connection material can secure a predetermined cross sectional area thereof at the connecting point of the via holes. Therefore, the resistance of interlayer connection can be prevented from increasing.
Further, an each multilayer substrate respectively described in twenty-fifth to twenty-seventh aspects of the present invention can be produced by the method respectively described in the fourteenth and sixteenth to twentieth aspects of the present invention.
Moreover, a multilayer substrate described in a twenty-eighth aspect of the present invention can be produced the method described in the twenty-first aspect of the present invention. A multilayer substrate described in a twenty-ninth aspect of the present invention can be produced the method described in the twenty-second aspect of the present invention.
Further, according to a thirtieth aspect of the present invention, the radial-shaped via holes in the twenty-ninth aspect may, concretely, have a crisscross pattern composed of four liner portions.
Moreover, a multilayer substrate described in a thirty-first aspect of the present invention can be produced the method described in the twenty-fourth aspect of the present invention.